Aroma is an important factor in determining the preference of food and drink, as its tastiness is an overall sensation of both taste and aroma. For example, coffee beverages are favorably and extensively consumed as a luxury grocery item. The flavor of each coffee beverage includes aroma, body, aftertaste and the like, and is characterized by roasted coffee beans used upon production of a coffee extract solution.
The aroma of a coffee extract solution can be classified, from the viewpoint of volatility thereof, into three parts which are a top note, a middle note and a last note. The top note is low in boiling point and high in volatility, and includes aroma components perceivable first. The last note is high in boiling point and low in volatility, and includes components that play a role of a residual aroma. The middle note has intermediate volatility and permanence between the top note and the last note, and includes components that play a central role of the aroma of the coffee extract solution.
As methods for collecting the top note out of these aroma components, it is known, for example, to have aroma components, which have vaporized as a result of heating of ground roasted coffee beans, carried by a carrier gas and to capture them with an organic solvent (Patent Document 1), and also to feed an ethanol-containing aqueous solution and an inert gas into contact with heated, ground roasted coffee beans and to condense and capture the resulting vaporized aroma components (Patent Document 2). As a method for collecting the last note which takes a position opposite to the top note, it has been proposed, for example, to subject a coffee extraction residue, which remains after extraction of coffee, to steam extraction and to recover the distillate (Patent Document 3). As a method for using the top note and the last note, it has also been proposed to blend an aroma solution, which has been obtained by capturing aroma components released upon grinding roasted coffee beans, with a condensed residual-fragrance solution, which has been extracted with an alkaline solution from a coffee extraction residue after extraction of coffee (Patent Document 4). These conventional methods all collect the top note from roasted coffee beans, and make no mention about its collection from a coffee extract solution.
With a view to avoiding reductions in taste and aroma due to a loss of a aroma component upon concentration of a coffee extract solution, on the other hand, a process has been proposed for the production of a concentrated coffee extract solution (Patent Document 5). According to this process, the coffee extract solution is concentrated through a reverse osmosis membrane to separate it into a concentrated solution and a free solution after concentration (permeation solution), the free solution after concentration is evaporated under reduced pressure to obtain from 3 to 25 wt % of a concentrated aroma solution, and the concentrated aroma solution is then mixed with the concentrated solution.
In recent years, as one of approaches for enhancing the preference of coffee beverages, a coffee beverage has been proposed (Patent Document 6). To impart anew flavor (clarity), this coffee beverage makes use of a coffee extract solution which has been brought into contact with a synthetic adsorbent after its treatment with activated carbon.